At present, there exist solutions able to provide hot foams, typically hot milk foams. These known existing solutions need to use two components: a whisk or a similar foaming element rotating within a container where milk is arranged, producing foam thanks to its rotation, and a heating element that heats the bottom part of the container and therefore heats the milk foam.
The heating element is typically configured as a thick film heater at the bottom part of the container or as an external element heating by induction this bottom part. In any of these configurations, the problem frequently arising is that there is a layer of milk being burnt on this bottom part of the container and firmly adhering to it: this presents a strong problem of hygiene and also highly complicates the cleaning of the container. Moreover, these known devices where the heating and frothing functions are separately incorporated, are more complex and more costly because of having more functional elements.
Some other solutions in the state of the art comprise steam pipes or steam venturi nozzles: these solutions are also able to froth a liquid and to heat it by using steam injection allowing heating and a specific design of the nozzle allowing frothing of the liquid. However, such solutions cannot provide a premium quality, fine and stable foam.
Document DE 20 2014 103 834 U1 discloses, for example, an immersion heating device heating a liquid arranged in a container by means of an induction plate that is introduced in the container. The most common liquid to heat with such a device is water, though no frothing would be possible with these devices either. A similar document known in the state of the art is for example US 2010/0170892 A1.
Document FR 2766048, for example, describes an electrical heating device using induction heating on an insertion element (inserted in a container where the fluid to heat is arranged) which is partly made of ferromagnetic material. This device does not allow to produce any foam and is only able to heat the fluid inside. Furthermore, it presents the problem of the fluid being burnt at the bottom part of the container and also on the insertion element itself.
There is therefore the need to provide a foaming device which is able to make hot foam on demand with a simple and compact configuration and solving the drawbacks mentioned in the state of the art, specially solving cleanability issues. The present invention is thus oriented towards these needs.